SG-HQ2 inhibits mast cell-mediated allergic inflammation through suppression of histamine release and pro-inflammatory cytokines

Ursolic acid inhibits FcεRI-mediated mast cell activation and allergic inflammation

BACKGROUND

Mast cells are the primary cells that play a crucial role in the allergic diseases via secretion of diverse allergic mediators. Ursolic acid (UA) is a naturally occurring anti-inflammatory triterpenoid possessing various biological properties such as immune regulation, antioxidant, and anti-fibrotic. The aim of this study was to evaluate the effects of UA in FcεRI-mediated mast cell activation and allergic inflammation.

METHODS

In this study, mast cells were stimulated with immunoglobulin E (IgE) and the anti-allergic effects of UA were assessed by measuring the levels of allergic mediators. In vivo effects of UA were observed by generating passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis (ASA) in mouse model.

RESULTS

We found that UA inhibited the degranulation of mast cell by suppressing the intracellular calcium level in a concentration-dependent manner. UA inhibited the expression and the release of pro-inflammatory cytokines in mast cells. Anti-allergic effects of UA were demonstrated via suppression of FcεRI-mediated signaling molecules. In addition, UA inhibited the IgE-mediated PCA and ovalbumin-induced ASA reactions in a dose-dependent manner.

CONCLUSIONS

Based on these findings, we suggest that UA might have potential as a therapeutic candidate for the treatment of allergic inflammatory diseases via inhibition of FcεRI-mediated mast cell activation.

The interplay between mast cells, pineal gland, and circadian rhythm: Links between histamine, melatonin, and inflammatory mediators

Our daily rhythmicity is controlled by a circadian clock with a specific set of genes located in the suprachiasmatic nucleus in the hypothalamus. Mast cells (MCs) are major effector cells that play a protective role against pathogens and inflammation. MC distribution and activation are associated with the circadian rhythm via two major pathways, IgE/FcεRI- and IL-33/ST2-mediated signaling. Furthermore, there is a robust oscillation between clock genes and MC-specific genes. Melatonin is a hormone derived from the amino acid tryptophan and is produced primarily in the pineal gland near the center of the brain, and histamine is a biologically active amine synthesized from the decarboxylation of the amino acid histidine by the L-histidine decarboxylase enzyme. Melatonin and histamine are previously reported to modulate circadian rhythms by pathways incorporating various modulators in which the nuclear factor-binding near the κ light-chain gene in B cells, NF-κB, is the common key factor. NF-κB interacts with the core clock genes and disrupts the production of pro-inflammatory cytokine mediators such as IL-6, IL-13, and TNF-α. Currently, there has been no study evaluating the interdependence between melatonin and histamine with respect to circadian oscillations in MCs. Accumulating evidence suggests that restoring circadian rhythms in MCs by targeting melatonin and histamine via NF-κB may be promising therapeutic strategy for MC-mediated inflammatory diseases. This review summarizes recent findings for circadian-mediated MC functional roles and activation paradigms, as well as the therapeutic potentials of targeting circadian-mediated melatonin and histamine signaling in MC-dependent inflammatory diseases.

Prunus serrulata var. spontanea inhibits mast cell activation and mast cell-mediated anaphylaxis

ETHNOPHARMACOLOGICAL RELEVANCE

A promising approach to treat a variety of diseases are considered as complementary and alternative herbal medicines. Prunus serrulata var. spontanea L. (Rosaceae) is used as herbal medicine to treat allergic diseases according to the Donguibogam, a tradition medical book of the Joseon Dynasty in Korea.

AIM OF THE STUDY

We prepared the aqueous extract of the bark of P. serrulata (AEBPS) and aimed to investigate the effects in mouse anaphylaxis models and various types of mast cells, including RBL-2H3, primary cultured peritoneal and bone marrow-derived mast cells.

MATERIALS AND METHODS

We used ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) and immunoglobulin (Ig) E-mediated passive cutaneous anaphylaxis (PCA) models, in vivo. The control drug dexamethasone (10 mg/kg) was used to compare the effectiveness of AEBPS (1-100 mg/kg). In vitro, IgE-stimulated mast cells were used to confirm the role of AEBPS (1-100 μg/mL). For statistical analyses, p values less than 0.05 were considered to be significant.

RESULTS

In ASA model, oral administration of AEBPS suppressed the hypothermia and increased level of serum histamine in a dose-dependent manner. AEBPS attenuated the serum IgE, OVA-specific IgE, and interleukin (IL)-4. Oral administration of AEBPS also blocked mast cell-dependent PCA. AEBPS suppressed degranulation of mast cells by reducing intracellular calcium level in mast cells. AEBPS inhibited tumor necrosis factor-α and IL-4 expression and secretion in a concentration-dependent manner through the reduction of nuclear factor-κB.

CONCLUSIONS

On the basis of these findings, AEBPS could serve as a potential therapeutic target for the management of mast cell-mediated allergic inflammation and as a regulator of mast cell activation.

The suppressive effect of dabrafenib, a therapeutic agent for metastatic melanoma, in IgE-mediated allergic inflammation

The functional inhibition of mast cells, which serve as a key effector cells in allergic reactions may be a specific target for treating immunoglobulin (Ig)E-mediated allergic reactions, which occur in various allergic diseases including anaphylaxis, asthma, and atopic dermatitis. In this study, we demonstrated the effects of dabrafenib, a therapeutic agent used to treat metastatic melanoma, with a focus on mast cell activation and local cutaneous anaphylaxis. In two types of mast cells (RBL-2H3 and mouse bone marrow-derived mast cells), dabrafenib (0.01, 0.1, 1 μM) pretreatment significantly decreased IgE-induced degranulation, intracellular calcium influx, and the activity of intracellular signaling molecules, such as Lyn, Syk, Akt, and PLCγ. Dabrafenib ameliorated mRNA and protein expression levels of interleukin-4 and tumor necrosis factor-α by the reduction of nuclear localization of nuclear factor-κB and nuclear factor of activated T-cells. In passive cutaneous anaphylaxis, oral administration of dabrafenib (0.1, 1, 10 mg/kg) reduced local pigmentation and ear thickness in a dose-dependent manner. Taken together, these results suggest that dabrafenib is a therapeutic drug candidate that controls IgE-mediated allergic inflammatory diseases through suppression of mast cell activity.

SG-SP1 Suppresses Mast Cell-Mediated Allergic Inflammation via Inhibition of FcεRI Signaling

Background: As the number of allergic disease increases, studies to identify new treatments take on new urgency. Epigallocatechin gallate (EGCG), a major component of green tea, has been shown to possess a wide range of pharmacological properties, including anti-inflammation and anti-viral infection. In previous study, gallic acid (GA), a part of EGCG, has shown anti-allergic inflammatory effect. To improve on preliminary evidence that GA has allergy mitigating effect, we designed SG-SP1 based on GA, and aimed to assess the effects of SG-SP1 on mast cell-mediated allergic inflammation using various animal and in vitro models.

Methods: For in vitro experiments, various types of IgE-stimulated mast cells (RBL-2H3: mast cell-like basophilic leukemia cells, and primary cultured peritoneal and bone marrow-derived mast cells) were used to determine the role of SG-SP1 (0.1–1 nM). Immunoglobulin (Ig) E-induced passive cutaneous anaphylaxis and ovalbumin-induced systemic anaphylaxis, standard animal models for immediate-type hypersensitivity were also used.

Results: For in vitro, SG-SP1 reduced degranulation of mast cells by down-regulating intracellular calcium levels in a concentration-dependent manner. SG-SP1 decreased expression and secretion of inflammatory cytokines in activated mast cells. This suppressive effect was associated with inhibition of the phosphorylation of Lyn, Syk and Akt, and the nuclear translocation of nuclear factor-κB. Due to the strong inhibitory effect of SG-SP1 on Lyn, the known upstream signaling to FcεRI-dependent pathway, we confirmed the direct binding of SG-SP1 to FcεRI, a high affinity IgE receptor by surface plasmon resonance experiment. Oral administration of SG-SP1 hindered allergic symptoms of both anaphylaxis models evidenced by reduction of hypothermia, serum IgE, ear thickness, and tissue pigmentation. This inhibition was mediated by the reductions in serum histamine and interleukin-4.

Conclusions: We determined that SG-SP1 directly interacts with FcεRI and propose SG-SP1 as a therapeutic candidate for mast cell-mediated allergic inflammatory disorders via inhibition of FcεRI signaling.

Inhibitory effects of orientin in mast cell-mediated allergic inflammation

BACKGROUND

Mast cells are immune effector cells mediating allergic inflammation by the secretion of inflammatory mediators such as histamine and pro-inflammatory cytokines. Orientin is a naturally occurring bioactive flavonoid that possesses diverse biological properties, including anti-inflammation, anti-oxidative, anti-tumor, and cardio protection. The objective of this study was to rule out the effectiveness of orientin in mast cell-mediated allergic inflammation.

METHODS

In this study, in vitro effects of orientin were evaluated in RBL-2H3, mouse bone marrow-derived mast cells, rat peritoneal mast cells, and in vivo effects were evaluated by inducing passive cutaneous anaphylaxis (PCA) in Imprinting Control Region (ICR) mice.

RESULTS

Findings show that orientin suppressed the immunoglobulin E (IgE)-mediated mast cell degranulation by reducing intracellular calcium level in a concentration-dependent manner. Orientin suppressed the secretion of pro-inflammatory cytokines in mast cells. This inhibitory effects of orientin was through inhibition of FcεRI-mediated signaling proteins. In addition, oral administration of orientin suppressed the IgE-mediated PCA reactions in a dose-dependent manner, which was evidenced by reduced Evan's blue pigmentation and ear swelling.

CONCLUSIONS

Based on these findings, we suggest that orientin might have potential to alleviate allergic reaction and mast cell-mediated allergic disease.

Commiphora myrrha inhibits itch-associated histamine and IL-31 production in stimulated mast cells

Commiphora myrrha (Myrrh) is widely recognized for its anti-inflammatory and antimicrobial properties, which are utilized for the treatment of oral ulcers, gingivitis, sinusitis, glomerulonephritis, brucellosis and a variety of skin disorders. The current study aimed to assess whether myrrh modulates itch-associated interleukin (IL)-31 cytokine production and histamine release in stimulated human mast cells (HMC-1). To realize this, molecular biology techniques including real-time quantitiative PCR, western blotting and ELISA were employed. The results indicated that Myrrh successfully suppressed phorbol myristate acetate and calcium ionophore-stimulated mRNA expression, and reduced the production of IL-31 in HMC-1 cells. In addition, myrrh served as a suppressor of extracellular signal-regulated kinase and NF-κB activation, indicating its mechanism in the prevention of HMC-1 cell IL-31 production. Myrrh also prevented the release of histamine in HMC-1 cells. Whilst the present study awaits in vivo support, the pharmacological actions of myrrh provide new indications as to its potential applicability for itch treatment, which cannot be treated with histamine receptor blockers alone.

Gomisin M2 Inhibits Mast Cell-Mediated Allergic Inflammation via Attenuation of FcεRI-Mediated Lyn and Fyn Activation and Intracellular Calcium Levels

Mast cells are effector cells that induce allergic inflammation by secreting inflammatory mediators. Gomisin M2 (G.M2) is a lignan isolated from Schisandra chinensis (Turcz). Baill. exhibiting anti-cancer activities. We aimed to investigate the anti-allergic effects and the underlying mechanism of G.M2 in mast cell–mediated allergic inflammation. For the in vitro study, we used mouse bone marrow–derived mast cells, RBL-2H3, and rat peritoneal mast cells. G.M2 inhibited mast cell degranulation upon immunoglobulin E (IgE) stimulation by suppressing the intracellular calcium. In addition, G.M2 inhibited the secretion of pro-inflammatory cytokines. These inhibitory effects were dependent on the suppression of FcεRI-mediated activation of signaling molecules. To confirm the anti-allergic effects of G.M2 in vivo, IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin-induced active systemic anaphylaxis (ASA) models were utilized. Oral administration of G.M2 suppressed the PCA reactions in a dose-dependent manner. In addition, G.M2 reduced the ASA reactions, including hypothermia, histamine, interleukin-4, and IgE production. In conclusion, G.M2 exhibits anti-allergic effects through suppression of the Lyn and Fyn pathways in mast cells. According to these findings, we suggest that G.M2 has potential as a therapeutic agent for the treatment of allergic inflammatory diseases via suppression of mast cell activation.

Avenanthramide C from germinated oats exhibits anti-allergic inflammatory effects in mast cells

Mast cells play a crucial role in allergic diseases via the release of inflammatory mediators, particularly histamine and pro-inflammatory cytokines. Avenanthramide (Avn) C, a polyphenol found mainly in oats, is known to exhibit various biological properties. In this study, we aimed to evaluate the effectiveness of Avn C from germinated oats against mast cell-mediated allergic inflammation. For the in vitro study, RBL-2H3, mouse bone marrow-derived mast cells and rat peritoneal mast cells were used. Avn C (1–100 nM) inhibited the immunoglobulin (Ig)E-stimulated mast cells degranulation by suppressing phosphorylation of phosphoinositide 3-kinase and phospholipase Cγ1 and decreasing intracellular calcium levels. It inhibited IgE-stimulated secretion of inflammatory cytokines via suppression of FcεRI-mediated signaling proteins Lyn, Syk, Akt, and nuclear factor-κB. To verify the effects of Avn C in vivo, ovalbumin-induced active systemic anaphylaxis (ASA) and IgE-mediated passive cutaneous anaphylaxis (PCA) models were used. Oral administration of Avn C dose-dependently attenuated the ASA reactions, as evidenced by the inhibition of hypothermia and reduction of elevated serum histamine, IgE, and interleukin-4 levels. Avn C also inhibited the PCA reactions, such as ear swelling and plasma extravasation. Our results suggested that Avn C from germinated oats might be a possible therapeutic candidate for mast cell-mediated allergic inflammation.

Nothofagin suppresses mast cell-mediated allergic inflammation

Mast cells play a major role in immunoglobulin E-mediated allergic inflammation, which is involved in asthma, atopic dermatitis, and allergic rhinitis. Nothofagin has been shown to ameliorate various inflammatory responses such as the septic response and vascular inflammation. In this study, we assessed the inhibitory effect of nothofagin on allergic inflammation using cultured/isolated mast cells and an anaphylaxis mouse model. Nothofagin treatment prevented histamine and β-hexosaminidase release by reducing the influx of calcium into the cytosol in a concentration-dependent manner. Nothofagin also inhibited the gene expression and secretion of pro-inflammatory cytokines such as tumor necrosis factor-α and interleukin-4 by downregulating the phosphorylation of Lyn, Syk, Akt and nuclear translocation of nuclear factor-κB. To confirm these effects of nothofagin in vivo, we used a passive cutaneous anaphylaxis mouse model. Topical administration of nothofagin suppressed local pigmentation and ear thickness. Taken together, these results suggest nothofagin as a potential candidate for the treatment of mast cell-involved allergic inflammatory diseases.

Stigmasterol Alleviates Cutaneous Allergic Responses in Rodents

The therapeutic potential of stigmasterol, a natural steroid alcohol with established immune-modulatory properties, was assessed on allergic cutaneous responses. We examined its suppressive effect on immunoglobulin E (IgE)-mediated active cutaneous anaphylaxis (ACA), compound 48/80 (C48/80)-induced pruritus, and irritant dermatitis induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). Stigmasterol at 10–100 mg/kg significantly inhibited ACA with reduction in reaction area and concentration of the extravasated Evans blue dye. Given at 50 and 100 mg/kg, stigmasterol significantly inhibited C48/80-induced scratching behaviour when compared to saline-treated C48/80-injected control. Skin histopathology of injected sites confirmed that stigmasterol reduced mast cell trafficking and degranulation associated with C48/80-induced pruritus. Stigmasterol controlled inflammatory features such as ear skin oedema and neutrophilia and also reduced serum levels of TNFα induced by topical application of TPA. Epidermal layer thickening and inflammatory cell infiltration of ear skin tissue were significantly reduced by stigmasterol. Taken together, stigmasterol demonstrates significant potential as a molecule of interest in allergic skin disease therapy.

Diospyros kaki calyx inhibits immediate-type hypersensitivity via the reduction of mast cell activation

CONTEXT

Diospyros kaki L. (Ebenaceae) fruit is widely distributed in Asia and is known to exert anti-inflammatory and antithrombotic effects.

OBJECTIVE

We evaluated the inhibitory effect of aqueous extract of D. kaki calyx (AEDKC) on mast cell-mediated immediate-type hypersensitivity and underlying mechanism of action.

MATERIALS AND METHODS

For in vivo, ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) and immunoglobulin (Ig) E-mediated passive cutaneous anaphylaxis (PCA) models were used. In the ASA, AEDKC (1-100 mg/kg) was orally administered 3 times during 14 days. In the PCA, AEDKC was orally treated 1 h before the antigen challenge. The control drug dexamethasone was used to compare the effectiveness of AEDKC. For in vitro, IgE-stimulated RBL-2H3 cells and primary cultured peritoneal mast cells were used to determine the role of AEDKC (0.01-1 mg/mL).

RESULTS

Oral administration of AEDKC dose dependently suppressed rectal temperature decrease and increases in serum histamine, total IgE, OVA-specific IgE, and interleukin (IL)-4 in the ASA. In the PCA, AEDKC reduced Evans blue pigmentation. Compared to dexamethasone (10 mg/kg), AEDKC (100 mg/kg) showed similar inhibitory effects in vivo. AEDKC concentration dependently suppressed the release of histamine and β-hexosaminidase through the reduction of intracellular calcium in mast cells. In addition, AEDKC decreased the expression and secretion of tumour necrosis factor-α and IL-4 by the reduction of nuclear factor-κB. The inhibitory potential of AEDKC (1 mg/mL) was similar with dexamethasone (10 μM) in vitro.

CONCLUSIONS

We suggest that AEDKC may be a potential candidate for the treatment of mast cell-mediated allergic diseases.

Formononetin ameliorates mast cell-mediated allergic inflammation via inhibition of histamine release and production of pro-inflammatory cytokines

Various allergic diseases cause allergic inflammation, which is mediated by mast cells. The current study investigated the anti-allergic inflammatory effects of formononetin and its mechanism of action in vitro using mast cells. Levels of histamine and pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6, were measured to assess the effects of formononetin on allergic inflammation. The activation of intracellular calcium and nuclear factor (NF)-κB, as well as the activity of caspase-1, were assessed to determine the mechanism of action. It was determined that difference concentrations of formononetin (0.1, 1 and 10 µM) suppressed histamine release and secretion of TNF-α, IL-1β and IL-6. Further investigations indicated that the effects of formononetin were associated with a reduction of intracellular calcium, suppression of NF-κB activation and upstream IκKα phosphorylation and inhibition of caspase-1 activity. Therefore, the results of the current study demonstrated that formononetin ameliorated mast cell-mediated allergic inflammation.

Evaluation of the central and peripheral effects of doxepin on carrageenan-induced inflammatory paw edema in rat

The anti-inflammatory effects of anti-depressants have been demonstrated recently. Doxepin, a tricyclic antidepressant drug (TCA), has some special properties in comparison with the other members of its family. It has some H1, H2, alpha-1 adrenergic and muscarinic receptor blocking effects. It revealed also anti-nociceptive and relatively potent sedative effects. This study was aimed to evaluate its possible anti-inflammatory effect in a well-established animal model. Male Wistar rats weighing 200-250 g were used in carrageenan-induced inflammatory paw edema model. The test and control drugs were injected by intraperitoneal (i.p.) and intracerebral (i.c.v.) routes. The anti-inflammatory activity of doxepin (15, 30 and 60 mg/kg, i.p. and 50 and 100 μg/rat, i.c.v.) and the reference drug, dexamethasone (2 mg/kg, i.p.) were evaluated by determination and comparison of some involved biological markers including the paw volume, cytokine levels (interleukin 6 (IL-6), IL-1β, tumor necrosis factor α (TNFα)), myeloperoxidase (MPO) activity and histopathological parameters. All i.p. doses of doxepin showed significant anti-inflammatory effect. It also significantly reduced MPO activity and cytokine levels and improved histopathologic parameters of carrageenan-injected paw tissues. I.c.v. administration of the drug did not show any significant reduction of carrageenan-induced paw edema. Although the exact mechanism of the anti-inflammatory effect of doxepin is not clear, it seems that reduced leukocyte migration and pro-inflammatory cytokines play important role in its anti-inflammatory effect. Also central sites are not involved in the anti-inflammatory effect of the drug.

Synthesis of Gallic Acid Analogs as Histamine and Pro-Inflammatory Cytokine Inhibitors for Treatment of Mast Cell-Mediated Allergic Inflammation

Gallic acid (3,4,5-trihydroxybenzoic acid), is a natural product found in various foods and herbs that are well known as powerful antioxidants. Our previous report demonstrated that it inhibits mast cell-derived inflammatory allergic reactions by blocking histamine release and pro-inflammatory cytokine expression. In this report, various amide analogs of gallic acid have been synthesized by introducing different amines through carbodiimide-mediated amide coupling and Pd/C-catalyzed hydrogenation. These compounds showed a modest to high inhibitory effect on histamine release and pro-inflammatory cytokine expression. Among them, the amide bearing (S)-phenylglycine methyl ester 3d was found to be more active than natural gallic acid. Further optimization yielded several (S)- and (R)-phenylglycine analogs that inhibited histamine release in vitro. Our findings suggest that some gallamides could be used as a treatment for allergic inflammatory diseases.

Chemoselective acylation of 2-amino-8-quinolinol in the generation of C2-amides or C8-esters

Chemoselective controls in acylation of 2-amino-8-quinolinol.

Quantitative determination of a synthetic amide derivative of gallic acid, SG-HQ2, using liquid chromatography tandem mass spectrometry, and its pharmacokinetics in rats

An amide derivative of gallic acid (GA), 3,4,5-trihydroxy-N-(8-hydroxyquinolin-2-yl)benzamide) (SG-HQ2) was recently synthesized, and its inhibitory actions were previously shown on histamine release and pro-inflammatory cytokine expression. In this study, a simultaneous quantification method was developed for the determination of SG-HQ2 and its possible metabolite, GA, in rat plasma using liquid chromatography with a tandem mass spectrometry (LC-MS/MS). After simple protein precipitation with acetonitrile including diclofenac (internal standard, IS), the analytes were chromatographed on a reversed phased column with a mobile phase of acetonitrile and water (60:40, v/v, including 0.1% formic acid). The ion transitions of the precursor to the product ion were principally protonated ion [M+H]⁺ at m/z 313.2→160.6 for SG-HQ2, and deprotonated ions [M-H]^- at m/z 168.7→124.9 for GA and 296.0→251.6 for the IS. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. This method was successfully applied to a pharmacokinetic study of SG-HQ2 after intravenous administration in rats.

Tyrosol Suppresses Allergic Inflammation by Inhibiting the Activation of Phosphoinositide 3-Kinase in Mast Cells

Allergic diseases such as atopic dermatitis, rhinitis, asthma, and anaphylaxis are attractive research areas. Tyrosol (2-(4-hydroxyphenyl)ethanol) is a polyphenolic compound with diverse biological activities. In this study, we investigated whether tyrosol has anti-allergic inflammatory effects. Ovalbumin-induced active systemic anaphylaxis and immunoglobulin E-mediated passive cutaneous anaphylaxis models were used for the immediate-type allergic responses. Oral administration of tyrosol reduced the allergic symptoms of hypothermia and pigmentation in both animal models. Mast cells that secrete allergic mediators are key regulators on allergic inflammation. Tyrosol dose-dependently decreased mast cell degranulation and expression of inflammatory cytokines. Intracellular calcium levels and activation of inhibitor of κB kinase (IKK) regulate cytokine expression and degranulation. Tyrosol blocked calcium influx and phosphorylation of the IKK complex. To define the molecular target for tyrosol, various signaling proteins involved in mast cell activation such as Lyn, Syk, phosphoinositide 3-kinase (PI3K), and Akt were examined. Our results showed that PI3K could be a molecular target for tyrosol in mast cells. Taken together, these findings indicated that tyrosol has anti-allergic inflammatory effects by inhibiting the degranulation of mast cells and expression of inflammatory cytokines; these effects are mediated via PI3K. Therefore, we expect tyrosol become a potential therapeutic candidate for allergic inflammatory disorders.